Jan 15, 2011: Wintry Mix For Tuesday

***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.

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Note: As I have been focusing more on the snow/ice threat for Tuesday, the storm summary for the January 11-12 storm was not posted tonight, however it will be posted tomorrow. In addition, the 5-Day Forecast page was updated for the area except for Long Island/S CT.

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Today was a partly to mostly cloudy day across the area, with more cloudy skies by the afternoon and scattered snow showers, especially north of New York City as a result of a low pressure that brought more widespread snowfall to the north of the area. Another cold air mass is currently moving into the area, and while tomorrow will not be very cold, tomorrow night is expected to be the coldest night so far this winter, with sub-zero low temperatures possible once again inland and high temperatures on Monday only in the upper 10s to mid 20s. As cold as this sounds, it is possible that even these lows may not be the coldest temperatures of the winter yet.


Tomorrow's Outlook:

Tomorrow will be a mostly to partly sunny day across the area with high temperatures once again above the 30 degree mark for parts of the area. High temperatures tomorrow will be in the upper 20s to lower 30s inland and in the lower to mid 30s for the rest of the area with a west wind expected.

As another arctic air mass moves into the area, low temperatures will quickly drop overnight, and may be even colder than those of yesterday morning according to the GFS model. There is some uncertainty with exactly how cold it gets, but the potential is there once again for interior areas to drop slighty below zero degrees, with single digits for most of the area away from the coast for Monday morning including the colder spots in eastern Long Island.


Early-Mid Week: Cold Monday Gives Way To A Wintry Mess On Tuesday

The week will start out on a very cold note, with high temperatures on Monday only peaking in the upper 10s to lower 20s inland and in the lower to mid 20s for the rest of the area. A few upper 20s are possible in the warmer spots from NYC and further south/SW, however these readings should not be widespread. An approaching storm, however, will change this, temporarily pushing out the cold air.


Model Analysis: There is still uncertainty with the exact set up on this event, with the models still showing a variety of solutions ranging from a low pressure hugging the coast with heavy rain and very little frozen precipitation as shown on the 18z NAM, to a coastal low that is further east and brings 1-3 inches of snow for the area on Monday morning followed by freezing rain/rain north and west of NYC as shown on the GFS. At this time, the GFS solution is the coldest one, with the other models showing warmer solutions. The 18z NAM, however, may have been perhaps a bit too warm, and for this forecast I am using a solution in between the GFS and the NAM but considering both extremes as possibilities.


Forecast For The Area: On Monday night, a low pressure off the Southeast coast along with another weak low pressure near the Great Lakes will push out the cold air mass, leading to warming temperatures on Monday night. Despite 850 mb temperatures warming up, we should see a cold air damming scenario, meaning that not all of the cold air gets pushed out. Light snow is expected to enter the area on Monday night, however any light snow should be brief for places south/east of New York City and will quickly change over to rain. For the immediate NYC area, the cold will hold around a little longer but will not be enough to keep the precipitation frozen the whole time, and while there is still uncertainty on the start of the event, it appears at this time that any snow to start should be light, with accumulations up to 1-2 inches, especially north and west of NYC, changing over to sleet/freezing rain by the morning and rain by the late morning. This is still subject to change though.

For the interior areas, however, the cold will stick around the longest, and after some light to potentially moderate snow to start, with accumulations potentially in the 1 to 3 inch range in the snowier solution, a longer period of freezing rain and/or sleet is expected than in areas closer to the coast. The interior area may also change over to at least some rain at this time, however depending on the storm set up, some places in the interior may not change over to rain at all and would stay with freezing rain in the colder scenario. For now, I put rain and freezing rain in the 5-Day Forecast for Tuesday afternoon, however this is subject to change. There could be enough freezing rain to lead to some ice accumulations, and I may issue a Freezing Rain Alert tomorrow.


There is still some uncertainty with this storm, and it is possible that the scenario may change. It is possible that we may see a warmer scenario, where NYC warms up into the lower to mid 40s with barely any frozen precipitation to start and heavy rain falling, ot we could see a colder scenario where the central and eastern parts of the area see at least 1-2 inches of snow followed by freezing rain persisting inland and only moderate rain for NYC further east. Stay tuned for more information on this storm and what impact it will have on the area.


Late Week - Weekend: Rain/Snow Possible Friday, Then Extreme Cold

While Wednesday is expected to be another relatively mild day, with temperatures similar to, if not slightly coler or warmer than those of Tuesday, in the mid 30s to lower 40s, yet another cold air mass will move into the area with cold overnight lows on Wednesday night, but not as cold as those of this morning and yesterday morning. High temperatures will return into the 20s for Thursday, however there is the possibility that another storm affects the area on Friday.

All of the models now show the Friday storm, and it is more of a question of how the storm will affect the area. The GFS only brings light snow to the area with the storm intensifying further offshore, however the ECMWF shows a solution completely different, close enough to the coast to bring a wintry mix for the immediate NYC area and more snow inland. While an inland track is unlikely at this time, it is a possibility that this storm could track over the cities, bringing mixing issues for parts of the area, but a plain rain storm is not expected at this time. A storm track that brings plain snow to the area is also a possibility. There is still uncertainty on this time frame, however, and some changes are expected with the models over the next few days. Stay tuned for more information on this storm.

Behind this storm, it appears that we may see the coldest temperatures of this winter and perhaps the biggest arctic outbreak since January 2009 if the coldest solutions verify. Most of the models bring 850 mb temperatures near or even slightly below -20c for the area, and while there is uncertainty on exactly how cold it gets, it is possible that most of the area only sees high temperatures in the 10s, with lows below zero degrees inland and the zero degree line potentially getting as far as the immediate N/W suburbs of NYC in the colder case scenario. Once again, it is still a possibility that the extreme scenario doesn't play out, and high temperatures only end up in the upper 10s to mid 20s range with low temperatures in the mid 0s to mid 10s, however at this time the cold scenario is starting to look more likely than it did yesterday. Stay tuned for more information in this time frame.